Theft of valuable small articles continues to be a problem for travelers and others who routinely transport valuable items in the normal course of their daily routines. Briefcases, luggage, portable computer carrying cases, camera bags, and other easily identifiable valuables make attractive targets for thieves. In particular, the theft of laptop computers has increasingly become a problem. Today, there are 50 million laptops in use throughout the world. By the year 2002, that number is expected to increase to more than 100 million. Unfortunately, the increasing popularity of laptop computers has spawned substantial black markets in both stolen computers and stolen confidential business data. These black markets have in part, driven the growth of computer and data theft, with a particularly troublesome effect of making airports notorious for computer theft.
Approaches to theft deterrence have varied in detail but usually consist of different combinations of motion or separation detectors, signaling devices for remote control, and alarm devices. For example, one existing system includes an alarmed luggage strap that triggers an alarm when a would-be thief opens a carrying case or luggage article encircled by the luggage strap. However, the device does not prevent the carrying case from being removed to a remote location before opening. Another approach is to provide an alarm for a security case which can be manually activated by the owner using a remote control. Unfortunately, these devices lack any provision to automatically detect theft attempts and the owner must remain attentive to trigger the alarm when a theft is attempted.
Several known devices trigger an alarm when two units (a detector unit and a transmitter unit) are separated by more than a preset distance. For example, one system discloses a device primarily used to deter kidnaping of a child but which may be used for luggage or other portable goods. This device generates a signal at the control unit and provides for an alarm trigger at the child unit. Other luggage alarm devices trigger alarms automatically when the owner or guardian of luggage (carrying one unit) walks away or is separated from, luggage (containing the second unit). Alarm devices based on separation distance do not distinguish between separation caused by movement of the protected article and separation as a result of the owner walking away temporarily. To protect against an article being removed by a thief, the separation distance at which an alarm occurs should be set as short as practical. However, for these devices to be convenient for routine travel, the distance at which the alarm occurs must be fairly large to avoid false alarms each time the owner places the protected article at rest and walks away to attend to other matters. As a result, the separation distance threshold is usually quite large because most travelers prefer not to have their routines distorted for an anti-theft device. Therefore, with separation distance based alarm devices, a theft attempt may not be detected until the protected article already has been moved a considerable distance from the owner.
Other known devices trigger an alarm when a motion sensing device detects movement of the protected article. Unlike the devices based on separation distance, motion sensing devices respond to an attempted theft instantaneously when the protected article is moved, but prior art motion sensing devices are prone to false alarms because they do not distinguish motion caused by the owner or an innocent passerby in a crowded environment from motion caused by a theft.
There remains a need for a theft deterrent system that is convenient in use, relatively free from false alarms and does not require frequent user action to arm and disarm the system.